The Moon will be more than half-full, in a so-called gibbous phase, which means its light will spoil stargazers' view in a similar way to that of urban light pollution.

"To be honest, it's not a good year for the Perseids," said Robert Massey, acting executive director of the Royal Astronomical Society (RAS) in London.

"You might, if you're lucky, see maybe 20 an hour," he told AFP.

The Perseids happen when Earth hits a belt of debris left behind by the comet Swift-Tuttle on its elongated, 133-year orbit around the Sun.

Each shooting star is a piece of comet dust, burning up from friction as it hits Earth's atmosphere.

Normally, Northern Hemisphere viewers are treated to a spectacle of about 100-120 visible shooting stars per hour when the phenomenon peaks around mid-August -- depending on the Moon and the weather.

Last year, there was an unusual "outburst" with more than double the usual fireball activity as Earth passed through especially dense "ribbons" of debris within the comet's dust belt.

"This year, we are expecting enhanced rates of about 150 (meteors) per hour or so, but the increased number will be cancelled out by the bright Moon, the light of which will wash out the fainter Perseids," states a NASA blog.

The Moon was full on August 7, and will have waned to approximately 80 percent illumination by Saturday.

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A photographer prepares to take pictures of the annual Perseid meteor shower in the village of Crissolo, near Cuneo, in the Monviso Alps region of northern Italy, on August 13, 2015. (Marco Bertorello/AFP)